U.S. patent application number 17/191619 was filed with the patent office on 2021-06-24 for display device.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. The applicant listed for this patent is SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Hoyoung AHN, Junhee CHOI, Joohun HAN, Kyungwook HWANG, Kiho KONG.
Application Number | 20210193733 17/191619 |
Document ID | / |
Family ID | 1000005434460 |
Filed Date | 2021-06-24 |
United States Patent
Application |
20210193733 |
Kind Code |
A1 |
HWANG; Kyungwook ; et
al. |
June 24, 2021 |
DISPLAY DEVICE
Abstract
A display device includes a substrate, an emissive layer; a
plurality of color converting layers that share the emissive layer,
a barrier arranged on the emissive layer between the plurality of
color converting layers, a first insulating layer provided between
the plurality of color converting layers and the emissive layer and
a second insulating layer provided between the first insulating
layer and the plurality of color converting layers. The barrier
spatially separates the plurality of color converting layers from
each other and the first insulating layer has a plurality of first
openings respectively corresponding to the plurality of color
converting layers.
Inventors: |
HWANG; Kyungwook;
(Hwaseong-si, KR) ; AHN; Hoyoung; (Suwon-si,
KR) ; CHOI; Junhee; (Seongnam-si, KR) ; KONG;
Kiho; (Suwon-si, KR) ; HAN; Joohun;
(Hwaseong-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRONICS CO., LTD. |
Suwon-si |
|
KR |
|
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
|
Family ID: |
1000005434460 |
Appl. No.: |
17/191619 |
Filed: |
March 3, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16557451 |
Aug 30, 2019 |
10971543 |
|
|
17191619 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 33/42 20130101;
H01L 33/507 20130101; H01L 27/156 20130101; H01L 33/58 20130101;
H01L 33/405 20130101; H01L 33/46 20130101 |
International
Class: |
H01L 27/15 20060101
H01L027/15; H01L 33/40 20060101 H01L033/40; H01L 33/58 20060101
H01L033/58; H01L 33/46 20060101 H01L033/46; H01L 33/50 20060101
H01L033/50; H01L 33/42 20060101 H01L033/42 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 13, 2018 |
KR |
10-2018-0109721 |
Claims
1. A display device comprising: an emissive layer implemented as a
single layer and configured to emit light; a plurality of color
converting layers provided on the emissive layer, each of the
plurality of color converting layers being arranged on a portion of
the emissive layer and configured to convert the light emitted by
the emissive layer into different color lights; at least one
barrier arranged on the emissive layer between the plurality of
color converting layers to spatially separate the plurality of
color converting layers from each other; a first insulating layer
provided between the plurality of color converting layers and the
emissive layer, the first insulating layer comprising a plurality
of first openings respectively corresponding to the plurality of
color converting layers; a second insulating layer provided between
the first insulating layer and the plurality of color converting
layers; and wherein at least a portion of a bottom surface of the
first insulating layer directly contacts an upper surface of the
emissive layer, a refractive index of the first insulating layer is
equal to or less than 1.6, the first insulating layer has a smaller
refractive index than the emissive layer, and the second insulating
layer has a smaller refractive index than the first insulating
layer.
2. The display device of claim 1, further comprising a plurality of
first electrodes respectively provided in the plurality of first
openings.
3. The display device of claim 2, wherein each of the plurality of
first electrodes respectively in contact with the emissive layer
through one of the plurality of first openings.
4. The display device of claim 2, wherein each of the plurality of
first electrodes extend from the bottom surface of the first
insulating layer to an upper surface the first insulating layer to
cover an entirety of a respective first opening of the plurality of
first openings.
5. The display device of claim 2, wherein at least one of the
plurality of first electrodes is transparent.
6. The display device of claim 2, further comprising a first
electrode pad that is in contact with a first electrode of the
plurality of first electrodes.
7. The display device of claim 6, wherein the first electrode pad
is provided in an area of the first electrode, which does not
overlap the plurality of first openings.
8. The display device of claim 1, wherein at least one of the first
and second insulating layers comprises at least one of SiO.sub.2,
SiN, Al.sub.2O.sub.3, and TiO.sub.2.
9. The display device of claim 1, wherein further comprising a
first reflective layer provided on the upper surface of the
emissive layer, the first reflective layer configured to reflect
the light incident from the emissive layer back into the emissive
layer.
10. The display device of claim 9, wherein an upper surface of the
first reflective layer and a side surface of the first reflective
layer are covered by the first insulating layer.
11. The display device of claim 9, wherein the first reflective
layer is provided between the plurality of first openings and
spaced apart from the plurality of first openings.
12. The display device of claim 10, wherein the first reflective
layer is provided between the plurality of first openings and
spaced apart from the plurality of first openings.
13. The display device of claim 2, further comprising a second
reflective layer provided on at least one of the plurality of first
electrodes and comprising a second opening that at least partially
overlaps one of the plurality of first openings.
14. The display device of claim 13, wherein at least a portion of
the second reflective layer overlaps the first insulating
layer.
15. The display device of claim 2, wherein at least one of the
plurality of first electrodes comprises a third opening overlapping
one of the plurality of first openings and extending along an upper
surface of the first insulating layer.
16. The display device of claim 2, further comprising a second
electrode contacting the emissive layer.
17. The display device of claim 16, wherein the plurality of first
electrodes are provided in a one-to-one correspondence with the
plurality of color converting layers, and the second electrode is
provided to correspond to at least one of the plurality of color
converting layers.
18. The display device of claim 16, wherein the emissive layer
includes a first semiconductor layer, an active layer, and a second
semiconductor layer that are sequentially provided, wherein each of
the plurality of first electrodes contacts the second semiconductor
layer, and wherein the second electrode contacts the first
semiconductor layer.
19. The display device of claim 18, wherein the second electrode
comprises: a via electrode passing through the first insulating
layer and contacting the first semiconductor layer; and a second
electrode pad provided on the first insulating layer and contacting
the via electrode.
20. The display device of claim 18, wherein the second electrode is
provided on a lower surface of the first semiconductor layer.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. application Ser.
No. 16/557,451, filed Aug. 30, 2019, which claims priority to
Korean Patent Application No. 10-2018-0109721, filed on Sep. 13,
2018, in the Korean Intellectual Property Office, the disclosures
of which are incorporated herein in their entirety by
reference.
BACKGROUND
1. Field
[0002] Example embodiments consistent with the present disclosure
relates to display devices and methods of manufacturing the display
devices, and more particularly, to display devices having an
improved color quality.
2. Description of the Related Art
[0003] As display devices, liquid crystal displays (LCD) and
organic light-emitting diode (OLED) displays are widely used.
Recently, the technique of manufacturing a high-resolution display
device by using a micro-light-emitting diode (LED) is drawing
attention. However, highly efficient compact LED chips are needed
for manufacturing high-resolution display devices, and a difficult
transfer technique is required to arrange compact LED chips at
appropriate positions.
SUMMARY
[0004] Provided is a high-resolution display device having an
improved optical efficiency and color quality.
[0005] Additional aspects will be set forth in part in the
description which follows and, in part, will be apparent from the
description, or may be learned by practice of the presented
embodiments.
[0006] In accordance with an aspect of the disclosure, there is
provided a display device comprising: a substrate; an emissive
layer provided on the substrate and configured to emit light; a
plurality of color converting layers provided on the emissive
layer, each of the plurality of color converting layers being
arranged on a portion of the emissive layer and configured to
convert the emitted by the emissive layer into different color
lights; at least one barrier arranged on the emissive layer between
the plurality of color converting layers to spatially separate the
plurality of color converting layers from each other; a first
insulating layer provided between the plurality of color converting
layers the emissive layer, the first insulating layer comprising a
plurality of first openings respectively corresponding to the
plurality of color converting layers; and a second insulating layer
provided between the first insulating layer and the plurality of
color converting layers.
[0007] A refractive index of at least one of the first and second
insulating layers may be equal to or less than 1.6.
[0008] At least one of the first and second insulating layers may
comprise at least one of SiO.sub.2, SiN, Al.sub.2O.sub.3, and
TiO.sub.2.
[0009] The display device may further comprise a first reflective
layer provided on an upper surface of the emissive layer, the first
reflective layer configured to reflect the light incident from the
emissive layer back into the emissive layer.
[0010] The upper surface and a side surface of the first reflective
layer may be covered by the first insulating layer.
[0011] The first reflective layer may comprise a metal.
[0012] The first reflective layer may be provided between the
plurality of first openings and spaced apart from the plurality of
first openings.
[0013] The display device may further comprise a plurality of first
electrodes provided on the emissive layer, each of the plurality of
first electrodes respectively in contact with the emissive layer
through one of the plurality of first openings.
[0014] At least one of the plurality of first electrodes may
comprise a transparent electrode, and wherein the one of the
plurality of first electrodes extends along an upper surface of the
first insulating layer.
[0015] The transparent electrode may contact an entire area of the
emissive layer exposed through the plurality of first openings.
[0016] The display device may further comprise a first electrode
pad that is in contact with the transparent electrode.
[0017] The first electrode pad may be provided in an area of the
transparent electrode, which does not overlap the plurality of
first openings.
[0018] The display device may further comprise a second reflective
layer provided on at least one of the plurality of first electrodes
and comprising a second opening that at least partially overlaps
one of the plurality of first openings.
[0019] At least a portion of the second reflective layer may
overlap the first insulating layer.
[0020] The second reflective layer may comprise a third reflective
layer and a fourth reflective layer that have different reflective
characteristics.
[0021] The third reflective layer may face the emissive layer,
wherein the fourth reflective layer faces one of the plurality of
color converting layers, and wherein the third reflective layer has
a reflectivity that is higher than a reflectivity of the third
reflective layer.
[0022] At least one of the plurality of first electrodes may
comprise a reflective electrode including a third opening
overlapping one of the plurality of first openings and extending
along an upper surface of the first insulating layer.
[0023] A first width of the third opening may be smaller than a
second width of the one of the plurality of first openings.
[0024] The second insulating layer may contact the emissive layer
through the first and third openings.
[0025] The display device may further comprise a second electrode
contacting the emissive layer.
[0026] The plurality of first electrodes may be provided in a
one-to-one correspondence with the plurality of color converting
layers, and the second electrode is provided to correspond to at
least one of the plurality of color converting layers.
[0027] The emissive layer may include a first semiconductor layer,
an active layer, and a second semiconductor layer that are
sequentially provided, wherein each of the plurality of first
electrodes contacts the second semiconductor layer, and wherein the
second electrode contacts the first semiconductor layer.
[0028] The second electrode may comprise: a via electrode passing
through the first insulating layer and contacting the first
semiconductor layer; and a second electrode pad provided on the
first insulating layer and contacting the via electrode.
[0029] The second electrode is provided on a lower surface of the
first semiconductor layer.
[0030] One of the at least one barrier may comprise at least one of
a black matrix that absorbs light, a resin, and a polymer.
[0031] One of the at least one barrier may comprise: a core; and a
shell surrounding a lateral surface of the core and reflecting
incident light.
[0032] The plurality of color converting layers may comprise at
least one of a red color converting layer emitting red color light,
a green color converting layer emitting green color light, and a
blue color converting layer emitting blue color light.
[0033] The emissive layer may generate at least one of blue color
light and ultraviolet rays.
[0034] The display device may further comprise a light absorbing
layer arranged on a lower surface of the emissive layer and
absorbing incident light.
[0035] In accordance with another aspect of the disclosure, there
is provided a display device comprising: a substrate; an emissive
layer provided on the substrate; a first color converting element
provided on a first section of the emissive layer and a second
color converting element provided on a second section of the
emissive layer; a barrier element provided between the first color
converting element and the second color converting element; and a
first insulating layer provided on the emissive layer, wherein the
first insulating layer comprises a first opening corresponding to
the first color converting element, and a second opening
corresponding to the second color converting element.
[0036] The first opening may be provided directly above the first
color converting element, and the second opening is provided
directly above the second color converting element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] These and/or other aspects will become apparent and more
readily appreciated from the following description of example
embodiments, taken in conjunction with the accompanying drawings in
which:
[0038] FIG. 1 is a cross-sectional view illustrating a display
device according to an example embodiment;
[0039] FIG. 2 is an expanded view of a region D of FIG. 1;
[0040] FIG. 3 is a cross-sectional view illustrating a display
device including a first electrode pad according to an example
embodiment;
[0041] FIG. 4 is a cross-sectional view illustrating a display
device including a first reflective layer according to an example
embodiment;
[0042] FIG. 5 is a cross-sectional view illustrating a display
device including a second reflective layer according to an example
embodiment;
[0043] FIG. 6 is a cross-sectional view illustrating a display
device including a second reflective layer according to another
example embodiment;
[0044] FIG. 7 is a cross-sectional view illustrating a display
device including first and second reflective layers according to
another example embodiment;
[0045] FIG. 8 illustrates a display device including a second
electrode according to another example embodiment;
[0046] FIG. 9 illustrates a display device including a second
electrode according to another example embodiment;
[0047] FIG. 10 illustrates a display device including a barrier
according to another example embodiment;
[0048] FIG. 11 illustrates a display device including a selective
transparent insulating layer, according to an example
embodiment;
[0049] FIG. 12 illustrates a display device including a selective
blocking layer, according to an example embodiment; and
[0050] FIG. 13 illustrate a display device including a light
absorbing layer, according to an example embodiment.
[0051] FIG. 14 illustrates a display device including a light
absorbing layer, according to an example embodiment.
DETAILED DESCRIPTION
[0052] Example embodiments will now be described more fully with
reference to the accompanying drawings. In the drawings, like
reference numerals denote like elements, and sizes of elements in
the drawings may be exaggerated for clarity and convenience of
description. Certain example embodiments described herein are
examples only, and may include various modifications.
[0053] Throughout the specification, it will also be understood
that when an element is referred to as being "on" another element,
it can be directly on the other element, or intervening elements
may also be present.
[0054] An expression used in the singular form encompasses the
expression in the plural form, unless it has a clearly different
meaning in the context. It is to be understood that the terms such
as "including", etc., are intended to indicate the existence of the
components, and are not intended to preclude the possibility that
one or more other components may added.
[0055] While such terms as "first," "second," etc., may be used
herein, the above terms are used only to distinguish one element
from another.
[0056] An expression used in the singular encompasses the
expression of the plural, unless it has a clearly different meaning
in the context.
[0057] Expressions such as "at least one of," when preceding a list
of elements, modify the entire list of elements and do not modify
the individual elements of the list.
[0058] FIG. 1 is a cross-sectional view illustrating a display
device 10 according to an example embodiment. FIG. 2 illustrates an
expanded view of a portion D of FIG. 1.
[0059] Referring to FIGS. 1 and 2, the display device 10 may
include a plurality of pixels. In FIG. 1, only two pixels are
illustrated for convenience. Each of the pixels may include
sub-pixels SR, SG, and SB, each configured to output different
colors from each other. In detail, the sub-pixels SR, SG, and SB
may respectively include a red sub-pixel SR, a green sub-pixel SG,
and a blue sub-pixel SB.
[0060] The display device 10 may include a substrate 110, an
emissive layer 120 arranged on the substrate 110, and a plurality
of color converting layers (130R, 130G, and 130B) arranged on the
emissive layer 120.
[0061] The substrate 110 may be a substrate used to grow the
emissive layer 120. The substrate 110 may include various materials
used in a typical semiconductor process. For example, a silicon
substrate or a sapphire substrate may be used as the substrate 110.
However, this is exemplary, and other various materials may also be
used as the substrate 110.
[0062] The emissive layer 120 emitting light is arranged on a upper
surface of the substrate 110. The emissive layer 120 may be an
inorganic material-based light-emitting diode (LED) layer. The
emissive layer 120 may emit, for example, blue color light B, but
is not limited thereto. The emissive layer 120 may emit light of a
certain wavelength according to a material included in the emissive
layer 120. The emissive layer 120 may be formed by sequentially
growing a first semiconductor layer 121, an active layer 122, and a
second semiconductor layer 123 on the upper surface of the
substrate 110.
[0063] The first semiconductor layer 121 may be arranged on the
upper surface of the substrate 110. The first semiconductor layer
121 may include, for example, an n-type semiconductor, but is not
limited thereto. The first semiconductor layer 121 may also include
a p-type semiconductor according to circumstances. The first
semiconductor layer 121 may include a Group III-V based n-type
semiconductor, for example, n-GaN. The first semiconductor layer
121 may have a single-layer or multi-layer structure.
[0064] The active layer 122 may be arranged on an upper surface of
the first semiconductor layer 121. The active layer 122 may emit
light as electrons and holes combine with each other. The active
layer 122 may have a multi-quantum well (MQW) structure, but is not
limited thereto, and may also have a single-quantum well (SQM)
structure according to circumstances. The active layer 122 may
include a Group III-V based semiconductor, for example, GaN. While
the active layer 122 is illustrated as a two-dimensional thin film
as an example, the active layer 122 is not limited thereto, and may
also have a three-dimensional shape such as a rod or pyramid
structure through growth performed using a mask. According to an
example embodiment, the active layer 122 may be arranged directly
on the upper surface of the semiconductor layer 121.
[0065] The second semiconductor layer 123 may be arranged on an
upper surface of the active layer 122. The second semiconductor
layer 123 may include, for example, a p-type semiconductor, but is
not limited thereto, and may include an n-type semiconductor
according to circumstances. The second semiconductor layer 123 may
include a Group III-V based p-type semiconductor, for example,
p-GaN. The second semiconductor layer 123 may have a single-layer
or multi-layer structure. According to an example embodiment, the
second semiconductor layer 123 may be arranged directly on the
upper surface of the active layer 122.
[0066] A plurality of color converting layers 130R, 130G, and 130B
that convert light emitted from the active layer 122 of the
emissive layer 120 to light of respective colors are arranged on
the emissive layer 120. According to an example embodiment, the
colors are predetermined colors. Each of the plurality of color
converting layers 130R, 130G, and 130B may be arranged on a portion
of the emissive layer 120. Thus, the plurality of color converting
layers 130R, 130G, and 130B may share one emissive layer 120. The
plurality of color converting layers 130R, 130G, and 130B may be
formed using a photolithography method.
[0067] For example, the plurality of color converting layers 130R,
130G, and 130B may include a red color converting layer 130R, a
green color converting layer 130G, and a blue color converting
layer 130B. Thus, the red color converting layer 130R and a portion
of the emissive layer 120 below the red color converting layer 130R
may be an element of a red sub-pixel SR; the green color converting
layer 130G and a portion of the emissive layer 120 below the green
color converting layer 130G may be an element of a green sub-pixel
SG; the blue color converting layer 130B and a portion of the
emissive layer 120 below the blue color converting layer 130B may
be an element of a blue sub-pixel SB.
[0068] The red color converting layer 130R may convert light
emitted from the active layer 122 to red color light R and emit the
same. The light emitted from the active layer 122 may be blue color
light. The red color converting layer 130R may include quantum dots
(QD) having a certain size, which are excited by blue color light
and emit red color light R. The quantum dots may have a core-shell
structure including a core portion and a shell portion or a
particle structure without shells. The core-shell structure may
have a single-shell or a multi-shell. The multi-shell may be, for
example, a double-shell.
[0069] The quantum dots may include at least one of, for example, a
Group II-VI based semiconductor, a Group III-V based semiconductor,
a Group IV-VI based semiconductor, a Group IV based semiconductor,
and graphene quantum dots. In detail, the quantum dots may include
at least one of Cd, Se, Zn, S, and InP, but are not limited
thereto. The quantum dots may have a diameter of several tens nm or
less, for example, a diameter of about 10 nm or less. In addition,
the red color converting layer 130R may include a phosphor that is
excited by blue color light generated in the active layer 122 to
emit red color light R. The red color converting layer 130R may
further include a photoresist having excellent transmitting
characteristics or a light dispersing agent that uniformly emits
red color light R.
[0070] The green color converting layer 130G may convert light
generated in the active layer 122 to green color light G and emit
the same. The active layer 122 may generate blue color light B. The
green color converting layer 130G may include quantum dots having a
certain size, which are excited by blue color light B to emit green
color light G. In addition, the green color converting layer 130G
may include a phosphor that is excited by blue color light B
generated in the active layer 122 to emit green color light G. The
green color converting layer 130G may further include a photoresist
or a light dispersing agent.
[0071] The blue color converting layer 130B may emit light
generated in the active layer 122 as blue color light B. When light
generated in the active layer 122 is blue color light B, the blue
color converting layer 130B may be a transmissive layer that
transmits through the blue color light B generated in the active
layer 122, without wavelength conversion. When the blue color
converting layer 130B is a transmissive layer, the blue color
converting layer 130B may not include quantum dots and may include
a photoresist or a light dispersing agent such as TiO.sub.2.
[0072] The display device 10 may further include at least one
barrier 140. According to an example embodiment, the plurality of
color converting layers 130R, 130G, and 130B are spatially spaced
apart from each other by the at least one barrier 140 provided
between the plurality of color converting layers 130R, 130G, and
130B. For example, the barrier 140 may be arranged between the red
color converting layer 130R and the green color converting layer
130G and between the green color converting layer 130G and the blue
color converting layer 130B. The barrier 140 may prevent color
mixture between lights emitted from the color converting layers
130R, 130B, and 130G to increase a level of contrast. The barrier
140 may include at least one of a black matrix material, a resin,
and a polymer.
[0073] The display device 10 may further include an insulating
layer 150 between the emissive layer 120 and the plurality of color
converting layers 130R, 130G, and 130B. The insulating layer 150
may be formed of a material having a smaller refractive index than
a refractive index of the emissive layer 120. The insulating layer
150 may be formed of an insulating material having a refractive
index of 1.6 or less. For example, the insulating layer 150 may
include SiO2, SiN, Al2O3 or TiO2, but is not limited thereto. Thus,
the insulating layer 150 may totally internally reflect light that
is incident to the emissive layer 120 at a greater angle of
threshold. For example, when the emissive layer 120 is formed of a
GaN material and the insulating layer 150 is formed of SiO.sub.2,
light incident to the insulating layer 150 at an angle of incidence
of about 35 degrees or greater is totally internally reflected to
proceed in a lateral direction of the emissive layer 120.
[0074] The insulating layer 150 may include a first insulating
layer 152 arranged on the emissive layer 120 and a second
insulating layer 154 arranged between the first insulating layer
152 and the plurality of color converting layers 130R, 130G, and
130B. The first insulating layer 152 may include a plurality of
first openings OP1 respectively corresponding to the plurality of
color converting layers 130R, 130G, and 130B. A current may be
applied to the emissive layer 120 through the first openings OP1,
and light generated in the emissive layer 120 may be incident to
the color converting layers 130R, 130G, and 130B, to which the
light corresponds, through the first openings OP1.
[0075] As a current may be applied through the first openings OP1,
the first openings OP1 may be referred to as a current injection
area, and since light is emitted from the emissive layer 120
through the first openings OP1, the first openings OP1 may be
referred to as a light emission area. Even when the plurality of
sub-pixels SR, SG, and SB share the emissive layer 120, the current
injection area may be localized such that light is generated in a
portion of the emissive layer 120 corresponding to a preset
sub-pixel through the first openings OP1. Thus, the light emission
area may be limited. Accordingly, effects due to optical
interference among sub-pixels may be reduced.
[0076] The second insulating layer 154 may be formed on the
emissive layer 120. According to an example embodiment, the second
insulating layer 154 may be formed on the entire upper surface of
the emissive layer 120 to increase total internal reflection
effects and insulating effects. The first insulating layer 152 and
the second insulating layer 154 may have an identical or different
refractive index. When the first insulating layer 152 and the
second insulating layer 154 have different refractive indices, the
second insulating layer 154 may have a smaller refractive index
than the refractive index of the first insulating layer 152. Thus,
light that is generated in the emissive layer 120 and has
transmitted through the first insulating layer 152 may also be
totally internally reflected by the second insulating layer
154.
[0077] The display device 10 may further include a first electrode
160 and a second electrode 170 that are electrically connected to
the emissive layer 120. The first electrode 160 may be electrically
connected to the second semiconductor layer 123 of the emissive
layer 120, and the second electrode 170 may be electrically
connected to the first semiconductor layer 121 of the emissive
layer 120. When the second semiconductor layer 123 includes a
p-type semiconductor, the first electrode 160 may be a p-type
electrode, and when the first semiconductor layer 121 includes an
n-type semiconductor, the second electrode 170 may be an n-type
electrode.
[0078] A plurality of first electrodes 160 may be included. The
number of first electrodes 160 may be equal to the number of
sub-pixels. That is, the first electrodes 160 may be respectively
spaced apart from each other in some regions of the emissive layer
120 to respectively correspond to the plurality of color converting
layers 130R, 130G, and 130B.
[0079] Each of the first electrodes 160 is in contact with the
emissive layer 120 through the first openings OP1, thus limiting an
area of contact between the first electrodes 160 and the second
semiconductor layer 123. Accordingly, a current injected from the
first electrodes 160 to the second semiconductor layer 123 may be
localized to the first openings OP1 described above. Thus, light
may be particularly generated only in an area of the active layer
122 below the color converting layers 130R, 130G, and 130B of a
particular color. The generated light may only be incident to the
color converting layers 130R, 130G, and 130B of a corresponding
color, through the first openings OP1, and is less likely to travel
to other sub-pixels in the vicinity. Even when light proceeds in a
different direction than towards the first openings OP1, the light
is totally internally reflected by the insulating layer 150 having
a smaller refractive index than the refractive index of the
emissive layer 120, and thus, light generated in a particular
sub-pixel is not emitted through other sub-pixels. Thus,
degradation in color quality may be reduced.
[0080] The plurality of first electrodes 160 may respectively be
arranged to correspond to a plurality of sub-pixels SR, SG, and SB,
that is, to the plurality of color converting layers 130R, 130G,
and 130B in a one-to-one correspondence. For example, the first
electrodes 160 may be respectively arranged below the red color
converting layer 130R, the green color converting layer 130G, and
130B
[0081] The first electrodes 160 may include a transparent
conductive material. For example, the first electrodes 160 may
include indium tin oxide (ITO), ZnO, indium zinc oxide (IZO), Ag,
Au, Ni, graphene or nanowires, but are not limited thereto. Thus,
light loss caused when light generated in the emissive layer 120 is
incident to the color converting layers 130R, 130G, and 130B
through the first electrodes 160 may be reduced.
[0082] The plurality of first electrodes 160 may also be
electrically connected to a plurality of thin film transistors in a
one-to-one correspondence. The thin film transistors selectively
drive at least one sub-pixel of the plurality of the sub-pixels SR,
SG, and SB.
[0083] The second electrode 170 may include a via electrode 172 and
a first electrode pad 174. According to an example embodiment, the
via electrode 172 passes through the first insulating layer 152 to
contact the emissive layer 120, for example, the first
semiconductor layer 121, and the first electrode pad 174. The first
electrode pad 174 is arranged on the first insulating layer 152 and
contacts the via electrode 172. A groove exposing the first
semiconductor layer 121 may be formed by sequentially etching the
second semiconductor layer 123, the active layer 122, and the first
semiconductor layer 121, and the second electrode 170 may be
provided in the groove. An insulating material may be formed on an
inner wall of the groove and on the second semiconductor layer 123
around the groove. The insulating material is identical to an
insulating material of the first insulating layer 152, and may be
formed when forming the first insulating layer 152. Also, the via
electrode 172 contacting the first semiconductor layer 121 may be
formed and the first electrode pad 174 that is in contact with the
first insulating layer 152 and the via electrode 172 may be
formed.
[0084] The second electrode 170 may be a common electrode providing
a common electrical signal to the plurality of sub-pixels SR, SG,
and SB. As a common electrical signal is provided to a plurality of
sub-pixels from one second electrode 170, the size of the
sub-pixels SR, SG, and SB may be reduced.
[0085] Referring to FIG. 1, the second electrode 170 is arranged to
commonly correspond to six sub-pixels SR, SG, and SB as an example.
However, this is an example, and the number of sub-pixels SR, SG,
and SG that commonly correspond to one second electrode 170 may
vary in various manners. The second electrode 170 may include a
highly conductive material.
[0086] In the above-described structure, when, for example, a thin
film transistor corresponding to a red sub-pixel SR is driven to
apply a certain voltage between the second electrode 170, which is
a common electrode, and the first electrode 160 corresponding to
the red sub-pixel SR, light is generated in a portion of the active
layer 122 located below the red color converting layer 130R. As the
generated light is incident to the red color converting layer 130R,
the red color converting layer 130R converts the light to red light
R to emit the same.
[0087] Alternatively, when a thin film transistor corresponding to
a green sub-pixel SG is driven to apply a certain voltage between
the second electrode 170, which is a common electrode, and the
first electrode 160 corresponding to the green sub-pixel SG, light
is generated in a portion of the active layer 122 located below the
green color converting layer 130G. As the generated light is
incident to the green color converting layer 130G, the green color
converting layer 130G emits green light G to the outside.
[0088] Alternatively, when a thin film transistor corresponding to
the blue sub-pixel SB is driven to apply a certain voltage between
the second electrode 170, which is a common electrode, and the
first electrode 160 corresponding to the blue sub-pixel SB, light
is generated in the active layer 122 located below the blue color
converting layer 130B. The generated light transmits through the
blue color converting layer 130B to be emitted to the outside. FIG.
2 illustrates an example in which red color light R, green color
light G, and blue color light B are respectively emitted from the
red color converting layer 130R, the green color converting layer
130G, and the blue color converting layer 130B to be emitted to the
outside.
[0089] According to the example embodiment, the display device 10
having a high resolution and an improved luminous efficiency may be
implemented. According to the related art, to implement a display
device 10 having a high resolution, compact LED chips corresponding
to the sub-pixels SR, SG, and SB are to be manufactured separately
and the compact LED chips need to be transferred at appropriate
positions. Here, the active layers 122 are separated from each
other for each sub-pixel, and thus, an exposed area of the active
layers 122 is increased to degrade luminous efficiency and
transferring the compact LED chips at accurate positions is
difficult.
[0090] In the display device 10 according to an example embodiment,
a plurality of sub-pixels SR, SG, and SB are arranged on one
emissive layer 120 (specifically, the active layer 122), and thus,
the manufacture of the display device 10 is easier than the related
art manufacturing method since the display device 10 may be
manufactured without transferring. In addition, the active layer
122, which is a light emission area, is not exposed for each
sub-pixel, and thus luminous efficiency may be increased.
[0091] Meanwhile, the active layer 122 is shared by a plurality of
sub-pixels, and thus, even when a most portion of the generated
light is incident to the color converting layers 130R, 130G, and
130B, to which the light corresponds, a portion of the light may
move in a lateral direction of the active layer 122 and proceed to
other sub-pixels. The light that proceeds to other sub-pixels may
be emitted to the outside through a color converting layer of other
sub-pixels to emit an undesired color and thus may degrade color
quality.
[0092] However, according to the display device 10 of the example
embodiment, a light emission area of the upper surface of the
emissive layer 120, that is, the area except the first openings
OP1, is covered by the insulating layer 150 having a smaller
refractive index than the emissive layer 120. Accordingly, light
incident at an angle of incidence equal to or greater than a
threshold angle is totally internally reflected at a boundary
between the insulating layer 150 and the emissive layer 120 to
thereby reduce emission of light through other sub-pixels.
[0093] FIG. 3 is a cross-sectional view illustrating a display
device 100a including a second electrode pad 162, according to an
example embodiment. When comparing FIGS. 2 and 3, the display
device 100a of FIG. 3 may further include a plurality of second
electrode pads 162 respectively contacting the plurality of first
electrodes 160. The second electrode pads 162 may respectively be
directly connected to electrodes of a thin film transistor. For
example, the second electrode pads 162 may be formed as the
electrodes of the thin film transistor are extended. The second
electrode pads 162 may be formed of a highly conductive material,
for example, a metal material. The second electrode pads 162 may be
arranged on an area of the first electrodes 160 that does not
overlap the first openings OP1. Thus, the second electrode pads 162
do not have to be transparent.
[0094] FIG. 4 is a cross-sectional view illustrating a display
device 100b including a first reflective layer 182, according to an
embodiment. When comparing FIGS. 2 and 4, the display device 100b
of FIG. 4 may further include a first reflective layer 182 that is
in contact with an upper surface of the emissive layer 120 and
reflects light incident from the emissive layer 120. An upper
surface and all lateral surfaces of the first reflective layer 182
may be covered by the insulating layer 150, specifically, the first
insulating layer 152. The first reflective layer 182 may be
arranged between the sub-pixels SR, SG, and SB. In detail, the
first reflective layer 182 may be arranged between the plurality of
first openings OP1 arranged in the emissive layer 120. The first
reflective layer 182 may be spaced apart from the first openings
OP1 such that the first reflective layer 182 does not overlap the
first openings OP1.
[0095] The first reflective layer 182 may be formed of a material
having a high light reflectivity and may include, for example, a
metal material. When light generated in the emissive layer 120 is
incident, the light may be reflected. Due to a smaller refractive
index of the insulating layer 150 than the emissive layer 120,
light incident at an angle that is equal to or greater than a
threshold angle may be totally internally reflected. However, a
portion of light incident at an angle less than the threshold angle
may transmit through the insulating layer 150 and be incident to a
color converting layer of an undesired other color. Light incident
to another color converting layer may be converted to light of
another color that is not desired and be emitted to the outside.
However, the first reflective layer 182 is arranged between the
first openings OP1, and thus, even when light is incident at an
angle less than the threshold angle, the light may be reflected by
the first reflective layer 182 to thereby prevent light incidence
to other color converting layers of other colors.
[0096] FIG. 5 is a cross-sectional view illustrating a display
device 100c including a second reflective layer 184, according to
an example embodiment. When comparing FIGS. 2 and 5, the display
device 100c of FIG. 5 may further include a second reflective layer
184 arranged on the first electrodes 160. The second reflective
layer 184 may cover at least a portion of an upper surface of the
first electrodes 160. The second reflective layer 184 may be formed
of a material having a high light reflectivity, and the second
reflective layer 184 may include, for example, a metal
material.
[0097] The second reflective layer 184 may include a plurality of
second openings OP2, and each of the second openings OP2 may
overlap at least a portion of a first opening OP1, among the
plurality of openings OP1 formed in the first insulating layer 152.
The second openings OP2 functions, in addition to the first
openings OP1, as a light path through which light generated in the
emissive layer 120 proceeds to the color converting layers 130R,
130G, and 130B. Also, light that is generated in the emissive layer
120 and does not pass through the first openings OP1 and the second
openings OP2 may be reflected by the insulating layer 150 or the
second reflective layer 184, thus preventing emission of the light
to the outside. According to an example embodiment, a width of each
of the second openings OP2 is smaller than a width of the
respective first openings OP1.
[0098] Moreover, in the second reflective layer 184, while light is
incident to the color converting layers 130R, 130G, and 130B, to
which the light corresponds, a portion of the light may be
reflected by the color converting layers 130R, 130G, and 130B. The
second reflective layer 184 reflects light that is not incident to
the color converting layers 130R, 130G, 130B again to the color
converting layers 130R, 130G, 130B, thereby increasing an
efficiency of light incident to the color converting layers 130R,
130G, 130B.
[0099] FIG. 6 is a cross-sectional view illustrating a display
device 100d including a second reflective layer 184a, according to
another example embodiment. When comparing FIGS. 5 and 6, the
display device 100d of FIG. 6 may not include first electrodes 160
but include only the second reflective layer 184a. The second
reflective layer 184a may be formed of a material having a high
reflectivity and also a high electrical conductivity. For example,
the second reflective layer 184a may be formed of a metal.
[0100] The second reflective layer 184a may perform not only a
function of reflecting light, but also a function as an electrode
through which a current is injected into the emissive layer 120.
Thus, the second reflective layer 184a may also be referred to as a
reflective electrode. For example, a first end of the second
reflective layer 184a may be in contact with the emissive layer 120
through one of the first opening OP1, and the other area of the
second reflective layer 184a may extend onto an upper surface of
the first insulating layer 152 along a lateral surface of the first
insulating layer 152. In addition, the second reflective layer 184a
also includes a plurality of third openings OP3, and each of the
third openings OP3 may overlap at least a portion of a respective
one of the first opening OP1. The third opening OP3 is smaller than
the first opening OP1 in size. According to an example embodiment,
a width of the third opening OP3 is smaller than a width of the
first opening OP1.
[0101] FIG. 7 is a cross-sectional view illustrating a display
device 100e including first and second reflective layers 182 and
184a, according to another embodiment. When comparing FIGS. 6 and
7, the display device 100e of FIG. 7 may further include a first
reflective layer 182 arranged between the emissive layer 120 and
the first insulating layer 152. The entire upper surface of the
first reflective layer 182 may be covered by the insulating layer
150. The first reflective layer 182 may be spaced apart from the
first openings OP1 on the emissive layer 120 between the first
openings OP1.
[0102] At least some portions of the first reflective layer 182 and
the second reflective layer 184a may overlap each other. Thus, when
viewing a pixel area of the display device 100e from above from the
display device 100e, a light path area of the upper surface of the
emissive layer 120, for example, an area except portions where the
first openings OP1 and the third openings OP3 overlap each other,
may be optically blocked by at least one of the first and second
reflective layers 182 and 184a. Thus, light generated in the
emissive layer 120 may be prevented from being emitted to other
areas than areas where the first openings OP1 and the third
openings OP3 overlap each other. Furthermore, an upper surface of
the second reflective layer 184a reflects light towards the color
converting layers 130R, 130G, and 1308, and thus, an efficiency of
light incident to the color converting layers 130R, 130G, 130B may
be increased.
[0103] At least one of the first reflective layer 182 and the
second reflective layers 184 and 184a may include two heterogeneous
layers having different optical characteristics. For example, the
first reflective layer 182 may include first and second layers
having different reflective characteristics. The first layer faces
the emissive layer 120 and may be formed of a material having a
relatively low reflectivity, and the second layer faces the color
converting layers 130R, 130G, and 130B and may be formed of a
highly reflective material. Thus, light that is reflected to
proceed towards the active layer 122 may increase reflection loss,
and light that is reflected and proceeds to the color converting
layers 130R, 130G, and 130B may increase a reflection efficiency.
In light proceeding to the active layer 122, light loss may occur
due to the first layer, and thus light interference may be reduced.
In light proceeding to the color converting layers 130R, 130G, and
130B, light loss is relatively small, and an efficiency of light
incident to the color converting layers 130R, 130G, 130B may be
increased accordingly.
[0104] The second reflective layers 184 and 184a also face the
emissive layer 120, and may include a first layer formed of a
material having a relatively low reflectivity and a second layer
facing the color converting layers 130R, 130G, 130B and formed of a
material having a relatively high reflectivity. The second
reflective layers 184 and 184a may also reduce light interference
by using the first layer and may increase a light efficiency by
using the second layer.
[0105] FIGS. 8 and 9 illustrate display devices 10b and 10c
respectively including second electrodes 170a and 170b, according
to another example embodiment. Comparing FIGS. 1 and 8, the second
electrode 170a illustrated in the display device 10b of FIG. 8 may
be arranged on a lower surface of the emissive layer 120. As the
second electrode 170a is arranged on the lower surface of the
second electrode 170a, a uniform distance with respect to the first
electrode 160 of each sub-pixel may be provided. Thus, a uniform
current path may be formed in the emissive layer 120 of each
sub-pixel.
[0106] The second electrodes 170b illustrated in the display device
10c of FIG. 9 may be spaced apart from each other for each
sub-pixel on a lower surface of the emissive layer 120. The first
electrodes 160 and the second electrodes 170b may be arranged in
units of sub-pixels in a one-to-one correspondence. As an
electrical signal is applied to the first electrodes 160 and the
second electrodes 170b in units of sub-pixels, light generated in
the emissive layer 120 included in other sub-pixels may be reduced.
When the substrate 110 is formed of a conductive material, the
substrate 110 may function as a second electrode.
[0107] In a vertical structure in which the second electrodes 170a
and 170b, the emissive layer 120, and the first electrodes 160 are
sequentially formed, there is no need to provide an additional area
to form the second electrodes 170 in the emissive layer 120, and
thus, a display device having a small sub-pixel or a small pixel
size may be implemented. Thus, a high-resolution display device may
be implemented.
[0108] FIG. 10 illustrates a display device 100f including a
barrier 140a according to another example embodiment. When
comparing FIGS. 2 and 10, the barrier 140a illustrated in FIG. 10
may include a core 142 and a shell 144. The shell 144 may include a
highly reflective material. For example, the shell 144 may be
formed of a metal material. When the barrier 140a is formed of a
black matrix material, light incident to a black matrix may be
absorbed, degrading an efficiency of light emitted to the color
converting layers 130R, 130G, and 130B. However, as the barrier
140a of FIG. 10 includes the shell 144 having reflective
characteristics, by reflecting light incident to the shell 144, a
light efficiency of light emitted from the color converting layers
130R, 130G, and 130B may be increased. The core 142 may be formed
of not only a black matrix, but also of an insulating material, a
photoresist material, or the like.
[0109] FIG. 11 illustrates a display device 100g including a
selective transparent insulating layer 210, according to an example
embodiment. When comparing FIGS. 2 and 11, the display device 100g
of FIG. 11 may further include a selective transparent insulating
layer 210 between the color converting layers 130R, 130G, and 130B
and the insulating layer 150. The transparent insulating layer 210
may transmit through light generated in the active layer 122 of the
emissive layer 120 and reflect light generated in a plurality of
color converting layers 130R, 130G, and 130B. The transparent
insulating layer 210 may include a structure including a plurality
of layers having different refractive indices.
[0110] FIG. 12 illustrates a display device 100h including a
selective blocking layer 220, according to an example embodiment.
When comparing FIGS. 2 and 12, the display device 100h of FIG. 12
may further include a selective blocking layer 220 arranged on the
color converting layers 130R, 130G, and 130B. The selective
blocking layer 220 may be arranged only on the red color converting
layer 130R and the green color converting layer 130G. The selective
blocking layer 220 may include a blue color blocking filter that
prevents blue color light B from being emitted to the outside from
the red color converting layer 130R and the blue color converting
layer 130B.
[0111] FIGS. 13 and 14 respectively illustrate display devices 100i
and 100j including a light absorbing layer 230, according to
example embodiments. The display device 100i or 100j may further
include a light absorbing layer 230 that absorbs light that is
generated in the emissive layer 120 and proceeds back to the
emissive layer 120. The light absorbing layer 230 may be arranged
on the emissive layer 120. For example, as illustrated in FIG. 13,
the light absorbing layer 230 may be arranged on a lower surface of
the substrate 110. The light absorbing layer 230 may absorb light
that is generated in the emissive layer 120 and transmits through
the substrate 110, thereby preventing light from being reflected by
a lower surface of the substrate 110 and proceeding to an upper
portion of the substrate 110. The light absorbing layer 230 may
include a material having a similar refractive index as that of the
substrate 110. For example, the light absorbing layer 230 may
include a polymer-based material. Alternatively, as illustrated in
FIG. 14, the light absorbing layer 230 may be arranged between the
emissive layer 120 and the substrate 110.
[0112] Although not illustrated in the drawings, a refractive index
matching layer may be arranged between the substrate 110 and the
first semiconductor layer 121. The refractive index matching layer
may reduce an amount of light reflected between the substrate 110
and the first semiconductor layer 121 due to a difference in the
indices of refraction of the substrate 110 and the first
semiconductor layer 121.
[0113] While blue color light B emitted from an active layer of the
display device has been described above as an example,
modifications may also be made such that ultraviolet ray (UV) is
emitted from the active layer.
[0114] The display devices 100a, 100b, 100c, 100d, 100e, 100f,
100g, 100h, 100i, and 100j of FIGS. 3 through 14 are described
based upon the display device 10 of FIG. 1 or the display device
100 of FIG. 2, but are not limited thereto. A display device may
also be implemented by combining the elements of the display
devices 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h, 100i, and
100j illustrated in FIGS. 3 through 14.
[0115] According to the example embodiments described above, as one
active layer 122 is formed to correspond to a plurality of color
converting layers 130R, 130G, and 130B, an exposed area of the
active layer 122 may be minimized, thereby increasing optical
efficiency. In addition, by using an insulating layer having a
small refractive index, an area of contact of a semiconductor layer
contacting an electrode may be limited to thereby not only reduce a
light emission area of the active layer but also increase a color
quality totally internally reflecting undesired light.
[0116] In addition, by arranging a reflective layer between an
emissive layer and a color converting layer, light incident from
the emissive layer is reflected to prevent emission of undesired
light and light incident from the color converting layer may be
reflected to increase an efficiency of emitted light.
[0117] Furthermore, by coating a reflective material on a barrier
between color converting layers, light incident from the color
converting layers may be reflected to thereby increase an
efficiency of emitted light.
[0118] According to example embodiments, one active layer is formed
to correspond to a plurality of color converting layers, such that
an area whereby the active layer is exposed may be minimized,
thereby increasing optical efficiency. In addition, by using an
insulating layer having a small refractive index, an area of
contact of a semiconductor layer contacting an electrode may be
limited to thereby not only reduce a light emission area of the
active layer but also increase a color quality by totally
internally reflecting undesired light.
[0119] In addition, by arranging a reflective layer between an
emissive layer and a color converting layer, light incident from
the emissive layer is reflected to prevent emission of undesired
light and light incident from the color converting layer may be
reflected to increase an efficiency of emitted light.
[0120] Furthermore, by coating a reflective material on a barrier
between color converting layers, light incident from the color
converting layers may be reflected to thereby increase an
efficiency of emitted light.
[0121] It should be understood that example embodiments described
herein should be considered in a descriptive sense only and not for
purposes of limitation. Descriptions of features or aspects within
each example embodiment should typically be considered as available
for other similar features or aspects in other embodiments.
[0122] While one or more example embodiments have been described
with reference to the figures, it will be understood by those of
ordinary skill in the art that various changes in form and details
may be made therein without departing from the spirit and scope as
defined by the following claims.
* * * * *